FORMOSAN SUBTERRANEAN TERMITE
UF/IFAS Photo by Thomas Chouvenc
Subterranean termites are the biggest threat the animal kingdom poses to Florida’s homes and businesses. The invasive Formosan subterranean termite leads the assault.
Estimated repair costs: a large but undetermined fraction of the $16.6 billion spent each year nationwide to repair damage caused by all termite species.
Estimated management costs: a large but undetermined fraction of the $3.3 billion spent each year nationwide on efforts to manage all termite species.
The U.S. accounts for half of global termite impact, and the Southeastern U.S. bears a disproportionate amount of the nationwide impact, because the region’s warm temperatures and high humidity offer favorable conditions conducive to termite nesting, growth and reproduction. In Florida, urbanized areas offer an abundance of lumber for pest termites. Also, the state’s status as a major destination for international tourism, travel and trade mean that Florida has a greater number of non-native organisms arriving than many states – termites among them. One invasive species, the Formosan subterranean termite, has become Florida’s most feared wood-destroying pest because it forms larger colonies than other termite species, and its workers forage over wider areas. Termite infestations rank among the most serious arthropod-related concerns for Florida property owners, and most homeowners’ insurance policies do not cover termite damage.
Common name: Formosan subterranean termite
Scientific name: Coptotermes formosanus
Good Bug or Bad Bug? Bad Bug
What It Is: The Formosan subterranean termite is a member of the insect order Blattodea, which includes cockroaches and termites. Within the Blattodea order, this species is part of the infraorder Isoptera, which includes termites only – about 3,100 species worldwide.
Most termite species exist in relative harmony with people, feeding on decaying plant matter and facilitating nutrient turnover and soil formation in natural environments. However, about 80 termite species worldwide are considered serious pests because they have certain attributes: They infest structures, form large colonies, and have a history of causing substantial economic damage.
Among those 80 pest species, subterranean termites are well-represented. The Formosan subterranean termite is part of the genus Coptotermes, which includes 28 species – 18 of which are considered serious pests.
The Formosan subterranean termite has a well-deserved reputation as the most troublesome termite species worldwide, for several reasons. First, this species forms larger colonies than most subterranean termites. All other things being equal, a large colony causes damage faster than a small one. Second, Formosan subterranean termite workers will forage as far as 100 meters from the nest in search of food, further than the foraging workers from other species. All other things being equal, termites that forage over larger areas are more likely to encounter structures. Third, the Formosan subterranean termite is distributed more widely than other invasive subterranean termites, and is now established in mainland China (its natural range), Taiwan, Japan, Hawaii, South Africa and the continental U.S. This fact speaks to the termite’s adaptability, but it is not clear whether the insect’s physical or behavioral attributes played a role in helping it successfully invade so many new environments. Finally, this species is resilient – there have been no reported instances of the Formosan subterranean termite being eradicated from any location it invaded and became established.
The Formosan subterranean termite was a seasoned world traveler long before its first reported appearance in Florida. The species was brought to Japan when the U.S. was still a British colony, and it arrived in Hawaii shortly before 1900. The pest was first reported in the continental U.S. in 1960, from three states – Louisiana, South Carolina and Texas. The first report from Florida came in 1980, from Hallandale, in Broward County. From there, the Formosan subterranean termite has expanded its range to include all parts of the state, and the species is now established in all major metropolitan areas of Florida. It is also present throughout much of the Southeast, though it has not advanced north of Tennessee and North Carolina.
Florida is also home to several native subterranean termites that infest structures. They account for a large percentage of the state’s termite-related damage. However, the Formosan subterranean termite is potentially more destructive. Although individual Formosan subterranean termites are not more voracious than native subterranean termites, the Formosan species forms colonies that can be far larger than those of native termites, so the overall damage caused by a single infestation can be much greater.
What It Does: As the name implies, subterranean termites nest in soil. Like other termites, subterranean species feed on woody plant materials, to obtain a compound called cellulose, a key component of plant cell walls. The vast majority of animals cannot obtain nutrients from cellulose, but termites can do so because their digestive systems contain symbiotic micro-organisms that chemically break down cellulose to yield the simpler compound acetate, which termites can digest.
Termites are social insects, and every colony contains three “castes” or types of termite, each with a different role to play – reproductives, soldiers and workers. From a pest-management standpoint, workers are the caste that people worry about most. Somewhere between 80 and 90 percent of the individuals in a subterranean termite nest are workers, and they spend their time foraging for sources of food. Workers shuttle back and forth from the nest to foraging sites in underground tunnels that they excavate. If the workers need to venture above ground, they construct tubes from a mud-like substance, which conceals the workers from view and provides the warm, moist conditions they need to survive.
Worker termites are blind but they communicate effectively with one another, using pheromones, vibrations and other means. When foraging workers locate wood that’s suitable to consume they leave a pheromone trail to lead others back to the find. If the new food source happens to be an untreated wood component in a building, workers may establish an ongoing infestation, gradually destroying the original infestation site and simultaneously roaming the building in search of new food sources. It’s been estimated that the workers in a large Formosan subterranean termite colony can collectively destroy almost one pound of wood each day
Formosan subterranean termite workers will also make speculative searches of any small spaces they can enter around the foundation of a building, including expansion joints, cracks in mortar and spaces around penetrations where pipes, wires and vents pass through walls. Again, if the foraging workers encounter food, they may start a new infestation.
Who Is Affected: Taking into account native and invasive species, subterranean termites can impact anyone in Florida who owns, rents or occupies a structure containing wood components. For this reason, it’s important for all Florida property owners to consider professional termite protection for their structures.
Where It’s Found in Florida: The Formosan subterranean termite can tolerate moderately cold temperatures and is established in every major metropolitan area of Florida. It has also been reported in Alabama, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee and Texas.
How It’s Currently Addressed: Subterranean termite treatment should be handled by pest-management professionals, it is not an undertaking for do-it-yourselfers.
The typical strategy for home and business owners is to engage a company to provide one-time treatment for active infestations, and/or have a company perform yearly inspections and treat when necessary. The most commonly used treatment for infestations is application of a liquid insecticide that is poured into the soil close to the exterior of the structure to be protected. Some experts have questioned whether the sheer size of the typical Formosan termite colony limits the effectiveness of liquid insecticide barriers, and whether this species is best managed via the use of poison baits. Although no formal UF/IFAS studies have been conducted on the issue, anecdotal evidence suggests that, unlike native subterranean termite species, colonies of Formosan subterranean termites can survive liquid insecticide treatment. All of these termite species are equally susceptible to the toxic effects of insecticides; the difference is that mature Formosan subterranean termite colonies are so large and expansive that it would require a more careful planning effort, and more liberal application of liquid insecticide, than is needed for management of native species. (You can learn more about termite protection and treatment in the feature story, “Termite Protection Plans” on the Bug Week website, http://bugs.ufl.edu.)
Native to Florida? No. The Formosan subterranean termite is native to Southern China and was first detected in Florida in 1980 in Hallandale, in Broward County. The species is now established in all of Florida’s major metropolitan areas. To see a current infestation map that’s regularly updated, visit http://flrec.ifas.ufl.edu/termites-in-florida/termite-distribution/.
Big Money Associates: Florida is home to three noteworthy native subterranean termites; the best-known is the eastern subterranean termite, Reticulitermes flavipes. These insects can damage structures but pose a less dire threat than the Asian and Formosan subterranean termites.
In recent years, another invasive subterranean termite has been detected in South Florida. Known as the Asian subterranean termite, or Philippine milk termite, this species has the scientific name Coptotermes gestroi, and is closely related to the Formosan subterranean termite. However, the Asian subterranean termite favors tropical conditions and has thus far been found only in South Florida. Part of the Asian subterranean termite’s range actually overlaps with the range of the Formosan subterranean termite, which prefers sub-tropical and temperate conditions.
South Florida is one of three places on Earth (the other two being Taiwan and Hawaii) where both species exist in the same place, and the situation has led to interbreeding between the termites. UF/IFAS researchers have been monitoring this situation, and are studying the hybrid termites that result when the Formosan and Asian species mate successfully. Though the hybrid’s potential impact is still unknown, experts fear that it may display a phenomenon known as “hybrid vigor” and be better suited to survive than either of its parent species. If the the hybrid were hardier or quicker to reproduce, for example, it might prove to be more destructive or more difficult to manage than the Formosan or Asian subterranean termite. However, UF/IFAS researchers have not collected enough data to make definitive statements on the threat the hybrid poses.
Interesting Fact: The largest known Formosan subterranean termite colony was found in a Louisiana public building, and contained an estimate 70 million termites.
Estimated Repair Costs in Florida: A large but undetermined fraction of the estimated $16.6 billion spent nationwide annually to repair damage caused by all termite species. The $16.6 billion figure is an estimate developed from 2010 data on pesticide sales; the actual figure in 2016 is probably slightly higher.
Estimated Management Costs in Florida: A large but undetermined fraction of the estimated $3.3 billion spent nationwide annually on management efforts for all termite species. The $3.3 billion figure is an estimate developed from 2010 data on pesticide sales; the actual figure in 2016 is probably slightly higher.
What Is UF Doing About It? Fortunately for Florida home and property owners, one of the world’s foremost authorities on subterranean termites is a long-time faculty member at the UF/IFAS Fort Lauderdale Research and Education Center. He is Dr. Nan-Yao Su, a distinguished professor with the UF/IFAS Department of Entomology and Nematology. Together with colleagues at Dow AgroSciences, Dr. Su developed a revolutionary approach to management of subterranean termites, which employs underground monitoring stations where foraging termites encounter appealing baits that containing a slow-acting compound that prevents immature termites from molting and kills them.
The technology was incorporated into the Sentricon® subterranean termite colony elimination system, which reached the consumer market in 1995 and has now protected more than 3 million homes in 18 countries and pre-empted the use of 9,000 metric tons of insecticide. The system is only available through licensed pest-management providers; when used properly, it poses no threat to people, pets, wildlife or water quality. Since reaching the market, Sentricon® has earned more than $29 million in royalties for UF, making it the third most valuable intellectual property ever developed at the university.
Su and his post-doctoral associate, Thomas Chouvenc, continue to research subterranean termites in South Florida, and are particularly focused on the hybrid Asian/Formosan termite that was identified recently, and may pose a serious threat to structures in South Florida.
Other UF/IFAS termite experts, including Rudolf Scheffrahn, Phil Koehler and Faith Oi, contribute to the UF/IFAS effort to research destructive structural termites of all types, update industry professionals, and educate Florida residents, particularly property owners.
What Can YOU Do About It? If you own a home or any other structure in Florida, educate yourself about the Formosan subterranean termite, the threat it poses to structures in this state, and options for protecting your investment. You can learn more in the feature story posted to the Bug Week website.
For more information about the Formosan subterranean termite, see this “Featured Creatures” document produced by the UF/IFAS Department of Entomology and Nematology.
For more information about the Asian subterranean termite, see:
For more information on native subterranean termites, see: http://entnemdept.ufl.edu/creatures/urban/termites/native_subterraneans.htm
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